Display device and operating method thereof

ABSTRACT

A display device includes a first substrate having light transmitting portions, a plurality of pixels positioned on the first substrate and including light emitting devices, a light sensor layer overlapping the first substrate and including light receiving devices respectively corresponding to the light transmitting portions, and a light guide layer positioned between the display panel and the light sensor layer and including light guide paths respectively corresponding to the light transmitting portions.

RELATED APPLICATION(S)

The present application claims priority under 35 U.S.C. 119(a) to KoreanPatent Application No. 10-2016-0123460, filed on Sep. 26, 2016, in theKorean Intellectual Property Office; the entire contents of the KoreanPatent Application are incorporated herein by reference.

BACKGROUND 1. Field

Embodiments relate to a display device and a method of operating thedisplay device.

2. Description of the Related Art

A display device may have a fingerprint sensing function. In the displaydevice, a fingerprint sensor may be attached to a predetermined area ofa display panel.

The fingerprint sensor may include, for example, a light source, a lens,and an image sensor. The fingerprint sensor may significantly add to thethickness and the manufacturing cost of the display device.

SUMMARY

According to an embodiment, a display device may have a fingerprintsensor without requiring an additional light source and may displayimage with satisfactory quality. An embodiment may be related to adriving/operating method of the display device.

According to an embodiment, a display device may include a display panelincluding a first substrate and a plurality of pixels (the pixels beingpositioned on the first substrate and including light emitting devices),a light sensor layer on the first substrate and including a plurality oflight receiving devices corresponding to light transmitting pathsbetween the plurality of pixels, and a light guide layer between thedisplay panel and the light sensor layer and including a plurality oflight guide paths corresponding to the light transmitting paths.

According to an embodiment, the pixels may be on a first surface of thefirst substrate, and the light sensor layer may be on a second surfaceof the first substrate.

The pixels may emit light in an upward direction relative to the firstsubstrate, and each of the light transmitting paths and each of thelight guide paths may transmit reflected light, which may be a portionof light emitted from at least one pixel and reflected by a user finger.

A Longitudinal direction of the light transmitting paths and the lightguide paths may be perpendicular to a plane in which the display panelis displayed.

A fingerprint sensor unit may be provided in the display device. Thefingerprint sensor unit may include at least one light transmittingpath, at least one light receiving device, and at least one light guidepath arranged to be overlapped with one another, among the lighttransmitting paths, the light guide paths, and the light receivingdevices.

A plurality of fingerprint sensor units may be arranged in an array formin a predetermined fingerprint sensor area.

The fingerprint sensor area may be arranged in at least one area of anactive area in which the pixels are arranged.

At least one area of the fingerprint sensor unit may overlap at leastone pixel.

The fingerprint sensor unit may overlap a boundary between immediatelyneighboring pixels.

The light transmitting paths may be arranged in peripheries of lightemitting devices included in at least a portion of the pixels.

The light transmitting paths may be arranged in spaces between lightshielding wires and circuit devices included in an active area in whichthe pixels are arranged.

The light guide layer may be a light shielding layer including aplurality of openings constituting the light guide paths.

The light guide layer may further include color filers filling theopenings.

The light guide layer may include optical fibers constituting the lightguide paths.

The light guide layer may further include a transparent insulating layerhaving a smaller refractive index than optical fibers and filling spacesbetween the optical fibers.

The optical fibers may include color filter materials included in acore.

The display device may further include a filter layer arranged betweenthe display panel and the light guide layer.

Each of the pixels may include a plurality of sub-pixels emitting lightin different colors, and the filter layer may be a color filterselectively transmitting light emitted from a portion of the pluralityof sub-pixels.

Each of the light receiving devices may generate an output signalcorresponding to light incident through each of the light transmittingpaths and each of the light guide paths.

A fingerprint shape on the display panel may be sensed by using outputsignals from the light receiving devices.

The display device may further include a touch sensor layer arranged inat least one area of an active area in which the pixels are arranged.

The touch sensor layer may include at least one touch sensor electrodearranged in a predetermined sensor area in which the light transmittingpaths, the light receiving devices and the light guide paths arearranged.

Pixels in a fingerprint sensor area including the light sensor layer mayselectively emit light in response to a control signal corresponding toa fingerprint sensing mode.

The pixels in the fingerprint sensor area may be divided into theplurality of pixels to form a plurality of groups, and the plurality ofpixels included in each group may sequentially emit light in response tothe control signal.

According to an embodiment, a method may be used for driving/operating adisplay device. The display device may include a display panel includinga plurality of pixels having light emitting devices for displaying animage in an active area, a light sensor layer arranged in a fingerprintsensor area positioned in the active area, and a light guide layerbetween the display panel and the light sensor layer. The methodincludes activating a fingerprint sensing mode in response to a controlsignal, turning on at least a portion of pixels arranged in thefingerprint sensor area, receiving light reflected from a fingerprintand/or a finger of a user, the light being received by the light sensorlayer after being transmitted via the light guide layer, generating anoutput signal corresponding to received light, and generatingfingerprint information using the output signal.

In the turning on of the at least the portion of the pixels arranged inthe fingerprint sensor area, the pixels in the fingerprint sensor areamay be divided into a plurality of groups, and pixels included in eachgroup may sequentially emit light.

In the turning on of the at least a portion of the pixels arranged inthe fingerprint sensor area, a fingerprint sensing period during whichthe fingerprint sensing mode is activated may be divided into aplurality of sub-periods, and a portion of pixels arranged with apredetermined distance among the pixels in the fingerprint sensor areamay emit light during each sub-period.

The display device may further include a touch sensor layer arranged inat least the fingerprint sensor area and generates the control signalcorresponding to a touch signal from the touch sensor layer.

The touch sensor layer, the light sensor layer, and the light guidelayer may be arranged in an entire active area, and an area in which thetouch signal is generated may be set to the fingerprint sensor area.

The fingerprint sensor area may be displayed by concurrently turning onat least a portion of pixels in the area in which the touch signal isgenerated.

The fingerprint sensor area may be displayed by concurrently turning onat least a portion of pixels in the fingerprint sensor area during aninitial period of a fingerprint sensing period during which thefingerprint sensing mode is activated.

An embodiment may be related to a display device. The display device mayinclude a first substrate having light transmitting portions, aplurality of pixels positioned on the first substrate and includinglight emitting devices, a light sensor layer overlapping the firstsubstrate and including a light receiving devices respectivelycorresponding to the light transmitting portions for outputting one ormore output signals in response to received light, and a light guidelayer positioned between the display panel and the light sensor layerand including light guide paths. The light guide paths may respectivelycorrespond to the light transmitting portions. The light guide paths maybe respectively connected to and/or aligned with the light transmittingportions.

The first substrate may be positioned between the plurality of pixelsand the light sensor layer.

The display device may include a second substrate, which may overlap thefirst substrate and may include light transmitting parts. The lighttransmitting parts respectively correspond to (and are respectivelyaligned with) the light transmitting portions. The pixels may emit lighttoward the second substrate and may be positioned between the firstsubstrate and the second substrate.

A longitudinal direction of each of the light transmitting portions anda longitudinal direction of each of the light guide paths may beperpendicular to a face of the first substrate on which the plurality ofpixels is arranged.

The display device may include a plurality of fingerprint sensor unitsincluding a first fingerprint sensor unit. The first fingerprint sensorunit may include a first light transmitting portion among the lighttransmitting portions, a first light receiving device among the lightreceiving devices, and a first light guide path among the light guidepaths. The first light transmitting portion, the first light receivingdevice, and the first light guide path may correspond to (and may bealigned with) one another.

The pixels include a first pixel. The first pixel may include twosubpixels immediately neighboring each other. A geometric axis of thefirst light guide path may coincide with a boundary between the twosubpixels.

In a predetermined portion of the display device a total quantity of thefingerprint sensors may be equal to a total quantity of the pixels ormay be equal to a fraction of the total quantity of the pixels.

The first fingerprint sensor unit may overlap at least one of thepixels.

The pixels include a first pixel. The first pixel may include twosubpixels immediately neighboring each other. The first light receivingdevice may be positioned at a boundary between the two subpixels.

The light guide paths include a first light guide path. The pixelsinclude a first pixel. The first pixel may include a first subpixel anda second subpixel immediately neighboring each other. The first lightguide path may be positioned between a light emitting device of thefirst subpixel and a transistor of the second subpixel (e.g., in a planview of the display device).

The first light guide path may be positioned between a first electrodeof the light emitting device of the first pixel and an active layer ofthe transistor of the second pixel (e.g., in a plan view of the displaydevice).

The light guide paths may be openings, through holes, or transparentportions of the light guide layer. The light guide layer may includelight shielding portions positioned between the light guide paths.

The light guide paths may include color filters. The light guide layermay include light shielding portions positioned between the colorfilers.

The light guide paths may include optical fibers.

The light guide layer further may include transparent insulatingportions positioned between the optical fibers. A refractive index ofeach of the transparent insulating portions may be less than arefractive index of each of the optical fibers.

A core of each of the optical fibers may include a color filtermaterial.

The display device may include a color filter layer positioned betweenthe first substrate and the light guide layer.

Each of the pixels may include a plurality of sub-pixels emitting lightin different colors. The different colors include a first color. Thecolor filter layer may have the first color.

The light guide paths include a first light guide path, which mayinclude a first cladding and a first core surrounded by the firstcladding. The light guide layer may include an insulating portionsurrounding the first cladding. A refractive index of the first core maybe greater than a refractive index of the first cladding. The refractiveindex of the first cladding may be greater than a refractive index ofthe insulating portion.

The light guide paths include a first light guide path. The pixelsinclude a first pixel. The first pixel may include a first subpixel anda second subpixel immediately neighboring each other. The first lightguide path may be positioned between a light emitting device of thefirst subpixel and a light emitting device of the second subpixel (e.g.,in a plan view of the display device).

The display device may include a touch sensor layer, which may includetouch sensor electrodes. The touch sensor electrodes may respectivelyoverlap the pixels and may respectively overlap the light guide paths.

The touch sensor electrodes include a first touch sensor electrode. Thelight guide paths include a first light guide path overlapping the firsttouch sensor electrode and positioned between a first edge of the firsttouch sensor electrode and a second edge of the first touch sensorelectrode. A minimum distance between the first edge of the first touchsensor electrode and the first light guide path may be greater than aminimum distance between the second edge of the first touch electrodeand the first light guide path.

A first subset of the pixels may emit light in response to a controlsignal to indicate a fingerprint sensing area when a second subset ofthe pixels emits no light. Pixels of the second subset may be positionedbetween pixels of the first subset and may separate the pixels of thefirst subset from one another.

The pixels may form a plurality of pixel groups. Pixels included inone/each of the pixel groups may sequentially emit light in response toa control signal.

An embodiment may be related to a method of operating a display device.The display device may include a first substrate, a plurality of pixelspositioned on the first substrate and having light emitting devices, alight sensor layer overlapping the first substrate, and a light guidelayer positioned between the first substrate and the light sensor layer.The method may include the following steps: starting a fingerprintsensing period in response to a control signal; turning on a firstsubset of the pixels during the fingerprint sensing period to emit firstlight toward at least one of a finger and a fingerprint; receivingsecond light using the light sensor layer. The second light may be aportion of the first light that may be reflected from the at least oneof the finger and the fingerprint and may be transmitted via the lightguide layer; generating an output signal corresponding to the secondlight; and generating fingerprint information using the output signal.

The method may include turning off or keeping off a second subset of thepixels when the first subset of the pixels is on. Pixels of the secondsubset may be positioned between pixels of the first subset and mayseparate the pixels of the first subset from one another.

The fingerprint sensing period may include a first sub-period and asecond sub-period immediately following the first sub-period. The firstsubset of the pixels may emit the first light in the first sub-period. Asecond subset of the pixels may emit no light in the first sub-period.The first subset of the pixels may emit no light in the secondsub-period. The second subset of the pixels may emit third light in thesecond sub-period.

The method may include generating the control signal in response to atouch provided by the finger on the display device.

The method may include the following steps: setting a fingerprintsensing area based on a location of the touch; and selecting the firstsubset of the pixels based on the fingerprint sensing area.

The method may include indicating, in response to the touch, thefingerprint sensing area by concurrently turning on at least pixels thatare located in an area of the display device corresponding to the touch.

The method may include indicating a fingerprint sensing area byconcurrently turning on the first subset of the pixels for apredetermined initial period of the fingerprint sensing period. Thefirst subset of the pixels may be located in the fingerprint sensingarea.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a plan view of a display device according to anembodiment.

FIG. 2 illustrates a plan view of a display device according to anembodiment.

FIG. 3 illustrates a plan view of a pixel according to an embodiment.

FIG. 4 is a circuit view/diagram illustrating a sub-pixel according toan embodiment.

FIG. 5 illustrates an embodiment of a layout of the sub-pixel shown inFIG. 4.

FIG. 6 is a circuit view/diagram illustrating a sub-pixel according toan embodiment.

FIG. 7 is a waveform view/diagram illustrating an embodiment of adriving method of the sub-pixel shown in FIG. 6.

FIG. 8 illustrates a plan view of a fingerprint sensor area (orfingerprint sensing area) of a display device according to anembodiment.

FIG. 9 illustrates a plan view of a fingerprint sensor area of a displaydevice according to an embodiment.

FIG. 10 illustrates a plan view of a fingerprint sensor area of adisplay device according to an embodiment.

FIG. 11 illustrates a plan view of a fingerprint sensor area of adisplay device according to an embodiment.

FIG. 12 illustrates a plan view of a fingerprint sensor area of adisplay device according to an embodiment.

FIG. 13 is a cross-sectional view illustrating a fingerprint sensor areaof a display device according to an embodiment.

FIG. 14 illustrates a light guide layer shown in FIG. 13 according to anembodiment.

FIG. 15 illustrates a light guide layer shown in FIG. 13 according to anembodiment.

FIG. 16 illustrates a light guide layer shown in FIG. 13 according to anembodiment.

FIG. 17 illustrates a method of fingerprint sensing of a display deviceaccording to an embodiment.

FIG. 18 is a cross-sectional view illustrating a fingerprint sensingarea of a display device according to an embodiment.

FIG. 19 is a cross-sectional view illustrating a fingerprint sensingarea of a display device according to an embodiment.

FIG. 20 is a flowchart illustrating a driving/operating method of adisplay device according to an embodiment.

FIG. 21 illustrates a driving method of pixels in a fingerprint sensingarea according to an embodiment.

DETAILED DESCRIPTION

Embodiments are described with reference to the accompanying drawings.Practical embodiments are not limited to the embodiments describedbelow, but may be modified into various forms.

Although the terms “first”, “second”, etc. may be used herein todescribe various elements, these elements, should not be limited bythese terms. These terms may be used to distinguish one element fromanother element. Thus, a first element discussed below may be termed asecond element without departing from teachings of one or moreembodiments. The description of an element as a “first” element may notrequire or imply the presence of a second element or other elements. Theterms “first”, “second”, etc. may also be used herein to differentiatedifferent categories or sets of elements. For conciseness, the terms“first”, “second”, etc. may represent “first-category (or first-set)”,“second-category (or second-set)”, etc., respectively.

FIGS. 1 and 2 illustrate a display device according to an embodiment.FIGS. 1 and 2 schematically show a display panel provided in a displaydevice according to an embodiment, and fingerprint sensor units disposedin at least one area of the display panel.

Referring to FIGS. 1 and 2, the display device according to anembodiment may comprise a display panel 10 including an active area 11and a non-active area 12.

A plurality of pixels PXL may be arranged in the active area 11.According to an embodiment, each of the pixels PXL may include at leastone light emitting element. The display device may display an image inthe active area 11 by driving the pixels PXL in response to input imagedata. In an embodiment, the active area 11 may be an effective displayarea of the display device.

According to an embodiment, a fingerprint sensor area 11 a may bedisposed in the active area 11. In an embodiment, the fingerprint sensorarea 11 a may be disposed in at least one area of the active area 11.For example, the fingerprint sensor area 11 a may be disposed only in aportion of the active area 11 as shown in FIG. 1.

According to an embodiment, the fingerprint sensor area 11 a may bedisposed in substantially the same area as the active area 11 as shownin FIG. 2. According to an embodiment, the active area 11 and thefingerprint sensor area 11 a may coincide with each other. In this case,a fingerprint sensing function may be provided or activated in theentire active area 11.

A plurality of fingerprint sensor units FSU may be disposed in thefingerprint sensor area 11 a. The fingerprint sensor units FSU mayconstitute a fingerprint sensor.

According to an embodiment, each of the fingerprint sensor units FSU mayuse a light emitting device provided in at least one pixel PXL in aperiphery of the fingerprint sensor units FSU as a light source forfingerprint sensing. To this end, the fingerprint sensor units FSU maybe disposed to be adjacent to at least one pixel PXL, or at least onearea of the fingerprint sensor units FSU may overlap the at least onepixel PXL.

The non-active area 12 (or non-displaying area 12) may be arranged in aperiphery of the active area 11. The non-active area 12 may be theremaining area, except for the active area 11. The non-active area 12may not be provided with the pixel PXL. In an embodiment, the non-activearea 12 may be a non-image-display area. According to an embodiment, thenon-active area 12 may include a wire routing area, a pad area, and/orvarious dummy areas.

According embodiments, the fingerprint sensor area 11 a having aplurality of fingerprint sensor units FSU may be provided in the activearea 11. As a result, the fingerprint sensing function may be providedin the active area 11. In an embodiment, in the display device, thefingerprint sensor may sense a fingerprint of a user sing light emittedfrom the pixels PXL without requiring an additional light source.Accordingly, the display device with a fingerprint sensing function mayhave a minimum thickness, and the manufacturing cost of the displaydevice may be minimized.

FIG. 3 illustrates a pixel according to an embodiment. In an embodiment,FIG. 3 shows an example of a pixel provided in a stripe-type displaydevice and consisting of three sub-pixels. The shape and the arrangementstructure of the pixels and/or the number of sub-pixels may be optimizedand/or configured according to particular embodiments. For example, anembodiment may be applied to a Pen-tile type display device.

Referring to FIG. 3, the pixel PXL may include a plurality of sub-pixelsSPX1, SPX2, and SPX3. For example, the pixel PXL may include first,second and third sub-pixels SPX1, SPX2, and SPX3 that emit light indifferent colors.

According to an embodiment, the first sub-pixel SPX1, the secondsub-pixel SPX2 and the third sub-pixel SPX3 may be a red sub-pixel, agreen sub-pixel, and a blue sub-pixel that emit red, green and bluelight, respectively. The pixel PXL may emit light of various colorsusing the plurality of sub-pixels SPX1, SPX2, and SPX3 that emit lightin different colors.

FIG. 4 is a circuit view illustrating a sub-pixel according to anembodiment. In an embodiment, FIG. 4 shows an active type sub-pixelconnected to an nth (n is a natural number) scan line and an mth (m is anatural number) data line and including two transistors.

Referring to FIG. 4, a sub-pixel SPX according to an embodiment mayinclude first and second transistors M1 and M2, a capacitor C, and alight-emitting device EL.

The first transistor M1 may be connected between a data line Dm and afirst node N1 and a gate electrode of the first transistor M1 may beconnected to a scan line Sn. The first transistor M1 may be turned onwhen a scan signal having a gate-on voltage (e.g., a low voltage) issupplied from the scan line Sn. When the first transistor M1 is turnedon, the data line Dm and the first node N1 may be electricallyconnected.

The second transistor M2 may be connected between a first power sourceELVDD and the light emitting device EL and a gate electrode of thesecond transistor M2 may be connected to the first node N1. The secondtransistor M2 may control a driving current supplied from the firstpower source ELVDD to a second power source ELVSS via the light emittingdevice EL corresponding to a voltage of the first node N1. According toan embodiment, the first power source ELVDD may be a high potentialpixel power source and the second power source ELVSS may be a lowpotential pixel power source.

The capacitor C may be connected between the first power source ELVDDand the first node N1. The capacitor C may store a voltage correspondingto a data signal supplied to the first node N1 and maintain the storedvoltage until a data signal of a subsequent frame is supplied.

The light emitting device EL may be connected between the secondtransistor M2 and the second power source ELVSS. The light emittingdevice EL may emit light of brightness corresponding to the drivingcurrent controlled by the second transistor M2. According to anembodiment, the light emitting device EL may be an organic lightemitting diode (OLED).

FIG. 5 illustrates an embodiment of a layout of the sub-pixel shown inFIG. 4. However, a layout shape of the sub-pixel may be optimized and/orconfigured in particular embodiments.

Referring to FIG. 5, the first transistor M1 may include a gateelectrode GE1 connected to the scan line Sn, an active layer AL1overlapping the gate electrode GE1, a source electrode SE1 contactedwith the active layer AL1 and connected to the data line Dm, and a drainelectrode DE1 contacted with the active layer AL1 and connected to afirst electrode CE1 of the capacitor C. The source electrode SE1 and thedrain electrode DE1 of the first transistor M1 may be switched with eachother according to the type of the first transistor M1 and/or thedirection of a voltage applied to the first transistor M1.

The capacitor C may include the first electrode CE1 connected to thedrain electrode DE1 of the first transistor M1 and a gate electrode ofthe second transistor M2 and a second electrode CE2 overlapping thefirst electrode CE1 and connected to a power source line PL to which thefirst power source ELVDD is applied.

The second transistor M2 may include a gate electrode GE2 connected tothe first electrode CE1 of the capacitor C, an active layer AL2overlapping a gate electrode GE2, a source electrode SE2 contacted withthe active layer AL2 and connected to the power source line PL to whichthe first power source ELVDD is applied, and a drain electrode DE2contacted with the active layer AL2 and connected to a first electrodeof the light emitting device EL, for example, an anode electrode AE. Thesource electrode SE2 and the drain electrode DE2 of the secondtransistor M2 may be switched with each other according to the type ofthe second transistor M2 and/or the direction of a voltage applied tothe second transistor M2.

The anode electrode AE may be electrically connected to the drainelectrode DE2 of the second transistor M2 through a via hole TH1. InFIG. 5, the anode electrode AE is illustrated not to overlap the firstand second transistors M1 and M2 and the capacitor C. In an embodiment,the anode electrode AE may be insulated from the transistors M1 and M2and the capacitor C and may overlap at least one of the transistors M1and M2 and the capacitor C. For example, in a top light emitting typedisplay device, the anode electrode AE may overlap with at least one ofthe first and second transistors M1 and M2 and the capacitor C.

A light emitting layer and a cathode electrode which are not shown maybe further disposed on the anode electrode AE. According to anembodiment, in the top light emitting type display device, the cathodeelectrode may be embodied as a transparent electrode so that lightgenerated in a light emitting layer may be transmitted.

Referring to an example of a layout of FIG. 5, a space in which a lightshielding element is not arranged may be included between circuitelements (for example, the first and second transistors M1 and M2, andthe capacitor C) constituting the sub-pixel SPX and/or wires (forexample, the scan line Sn, the data line Dm, and the power source linePL). In an embodiment, there is a space in which the light shieldingelement is not disposed between adjacent sub-pixels SPX. In anembodiment, a plurality of spaces in which light is transmitted may beprovided in the active area 11, and each of the spaces may constitute alight transmitting path.

FIG. 6 is a circuit view illustrating a sub-pixel according to anembodiment. In FIG. 6, the similar or same elements as in FIG. 4 aredenoted by the same reference numerals.

Referring to FIG. 6, the sub-pixel SPX according to an embodiment mayfurther include a third transistor M3. The third transistor M3 may beconnected between the second transistor M2 and the light emitting deviceEL and a gate electrode of the third transistor M3 may be connected to alight emitting control line En. The third transistor M3 may be turned onor off in response to a light emitting control signal supplied from thelight emitting control line En. According to an embodiment, the lightemitting control signal may have a gate-off voltage (e.g., a highvoltage) that turn off the third transistor M3. In such a case, thethird transistor M3 may be turned off when the light emitting controlsignal is supplied to the light emitting control line En, and in othercases, the third transistor M3 may be turned on when a voltage of thelight emitting control signal is set to the gate-on voltage.

When the third transistor M3 is turned on, the second transistor M2 andthe light emitting device EL may be electrically connected to eachother. Accordingly, a current path from the first power source ELVDD tothe second power source ELVSS may be formed via the second transistorM2, the third transistor M3 and the light emitting device EL.

In embodiments, in FIGS. 4 to 6, a relatively small number oftransistors, for example, active type sub-pixels SPX having a simplestructure including the first, second and/or third transistors M1, M2and M3 and one capacitor C are shown as examples. In an embodiment, thestructures of the sub-pixels SPX and/or the pixels PXL may be differentfrom the structures discussed above.

For example, each sub-pixel SPX may further include one or moretransistors which are not shown in addition to the first, second, andthird transistors M1, M2, and M3. For example, each sub-pixel SPX mayfurther include at least one of a fourth transistor for diode-connectingthe driving transistor for compensating a threshold voltage of thedriving transistor (i.e., the second transistor M2), a fifth transistorfor initializing a gate voltage of the driving transistor (i.e., avoltage of the first node N1), a sixth transistor for controlling theconnection between the first power source ELVDD and the drivingtransistor, and a seventh transistor for initializing an anode voltageof the light emitting device EL. In an embodiment, as the pixelstructure is changed, the position of the capacitor C may be changed, orat least one capacitor (not shown) in addition to the capacitor C may beadditionally provided in each sub-pixel SPX.

FIG. 7 is a waveform view illustrating an embodiment of a driving methodof the sub-pixel shown in FIG. 6.

Referring to FIG. 7, the light emitting control signal of the gate-offvoltage (for example, a high voltage) may be supplied to the lightemitting control line En before a scan signal of the gate-on voltage(for example, a low voltage) is supplied to the scan line Sn. The lightemitting control signal may be supplied for at least a period duringwhich the scan signal is supplied and the light emitting control signalis not supplied after the supply of the scan signal is stopped. In anembodiment, the voltage of the light emitting control signal may bechanged to the gate-on voltage (for example, a low voltage) after thesupply of the scan signal is completed and the voltage of the scan lineSn is changed to the gate-off voltage (for example, a high voltage).When the light emitting control signal of the gate-off voltage issupplied to the light emitting control line En, the third transistor M3may be turned off. As a result, the driving current to the lightemitting device EL may not be supplied.

In a period during which the light emitting control signal is suppliedto the light emitting control line En, the scan signal of the gate-onvoltage may be supplied to the scan line Sn. When the scan signal issupplied to the scan line Sn, the first transistor M1 may be turned onand the data line Dm and the first node N1 may be electricallyconnected. Thus, a data signal DS from the data line Dm may be suppliedto the first node N1. A voltage corresponding to the data signal DS, forexample, a difference voltage between the first power source ELVDD andthe data signal DS may be stored in the capacitor C.

After a voltage corresponding to the data signal DS is stored or chargedin the capacitor C, the supply of the light emitting control signal maybe stopped. In an embodiment, after the data signal DS is stored in thesub-pixel SPX, the voltage of the light emitting control signal may bechanged to the gate-on voltage. Thus, the third transistor M3 may beturned. When the third transistor M3 is turned on, the second transistorM2 and the light emitting device EL may be electrically connected toeach other. Accordingly, a current path of a driving current from thefirst power source ELVDD to the second power source ELVSS via the secondtransistor M2, the third transistor M3 and the light emitting device ELmay be formed. The second transistor M2 may control the amount of thedriving current corresponding to the voltage of the first node N1, andthe light emitting device EL may emit light of a brightnesscorresponding to the amount of the driving current. When the data signalDS corresponding to a black grayscale is supplied during the periodduring which the scan signal is supplied, the second transistor M2 mayblock the driving current from flowing to the light emitting device EL.Accordingly, the light emitting device EL may emit no light during afirst frame (1F) to express the black grayscale.

The sub-pixel SPX described above may control the amount of drivingcurrent by the second transistor M2 and control the formation of thecurrent path by the third transistor M3. Therefore, when at least onepixel PXL disposed in a predetermined area (for example, the fingerprintsensor area 11 a) emits light during a predetermined period (forexample, a fingerprint sensing period), the emission of the pixel PXLmay be easily controlled by using the scan signal and/or the data signaltogether with the light emitting control signal.

FIGS. 8 to 12 illustrate a fingerprint sensor area of a display deviceaccording to embodiments.

Referring to FIGS. 8 to 12, the fingerprint sensor may include theplurality of fingerprint sensor units FSU distributed in the fingerprintsensor area 11 a. As described in FIGS. 1 and 2, the fingerprint sensorarea 11 a may be a portion of the active area 11, or an entire area ofthe active area 11.

According to an embodiment, a plurality of fingerprint sensor units FSUmay be regularly arranged in the fingerprint sensor area 11 a. Accordingto an embodiment, the fingerprint sensor units FSU may be distributedirregularly in the fingerprint sensor area 11 a.

According to an embodiment, each of the fingerprint sensor units FSU mayuse the light emitting device EL provided in at least one pixel PXL, forexample, one or more light emitting devices EL included in the first tothird sub-pixels SPX1, SPX2 and SPX3 may be used as a light source. Atleast one area of each of the fingerprint sensor units FSU may overlapat least one pixel PXL, or at least one of the fingerprint sensor unitsFSU may be disposed in an area between adjacent pixels PXL.

Referring to FIG. 8, according to an embodiment, the fingerprint sensorunits FSU may be disposed at the same resolution as the pixels PXL atleast in the fingerprint sensor area 11 a. In an embodiment, thefingerprint sensor unit 11 a may include fingerprint sensor units FSU asmany as the number of pixels PXL. According to an embodiment, at leastone portion of each of the fingerprint sensor units FSU may overlap withat least one pixel PXL. For example, each of the fingerprint sensorunits FSU may be disposed in an area in which one pixel PXL is formed.

Referring to FIG. 9, according to an embodiment, the fingerprint sensorunits FSU may be arranged at a predetermined distance in the fingerprintsensor area 11 a with a smaller number than that of the pixels PXL. Forexample, the fingerprint sensor units FSU may be disposed in an area inwhich a portion of the pixels PXL disposed in the fingerprint sensorarea 11 a is formed. FIG. 9 discloses an embodiment in which onefingerprint sensor unit FSU per four pixels PXL is disposed in thefingerprint sensor area 11 a. The number or resolution of fingerprintsensor units FSU provided in the fingerprint sensor area 11 a may beconfigured and/or optimized in particular embodiments.

Referring to FIG. 10, according to an embodiment, each of thefingerprint sensor units FSU may have a larger size than an individualpixel PXL and be arranged in an area including the pixel PXLcorresponding to each of the fingerprint sensor units FSU.

Referring to FIG. 11, according to an embodiment, each of thefingerprint sensor units FSU may be disposed at boundaries betweenimmediately neighboring pixels PXL. At least one area of each of thefingerprint sensor units FSU may overlap the immediately neighboringpixels PXL.

Referring to FIG. 12, according to an embodiment, each of thefingerprint sensor units FSU may be disposed between immediatelyneighboring pixels PXL, but in a space between the pixels PXL so as notto overlap the pixels PXL.

As illustrated in FIGS. 8 to 12, the size, number, resolution, positionand/or arrangement structure of the fingerprint sensor units FSUprovided in the fingerprint sensor area 11 a may be configured and/oroptimized according to particular embodiments. For example, inconsideration of various factors such as the amount of received light,the resolution and/or the cross-talk required by individual fingerprintsensor unit FSU for fingerprint sensing, the size, number, resolution,location and/or arrangement structure of the fingerprint sensor unitsFSU may be determined.

FIG. 13 is a cross-sectional view illustrating a fingerprint sensor areaof a display device according to an embodiment. FIG. 13 shows elementsconstituting sub-pixels. In FIG. 13, the sizes of the pixels areexaggerated compared to a size of a finger to clearly show each of thesub-pixels and the fingerprint sensor unit. However, actual sizes of theindividual pixels and the fingerprint sensor units and a related pitchmay be very small. In an embodiment, a plurality of pixels andfingerprint sensor units may be disposed under the fingerprint (orfingertip), and a fingerprint shape (a fingerprint pattern) may bedetected/determined by synthesizing output signals from the fingerprintsensor units.

Referring to FIG. 13, the display device may include a plurality offingerprint sensor units FSU disposed in the fingerprint sensor area 11a. Each fingerprint sensor unit FSU may include a light transmittingpath 150, a light guide path 210, and a light receiving device 310corresponding to one another. For example, each fingerprint sensor unitFSU may include at least one light transmitting path 150, at least onelight guide path 210, and at least one light receiving device 310arranged to overlap with one another, among a plurality of lighttransmitting paths 150, light guide paths 210, and light receivingdevices 310. The fingerprint sensor unit FSU may use at least one lightemitting device 115 included in a neighboring pixel PXL as a lightsource for fingerprint sensing. Therefore, in addition to the lighttransmitting paths 150, the light guide paths 210 and the lightreceiving devices 310 corresponding to one another, at least one lightemitting device 115 provided in the neighboring pixel PXL may constituteeach fingerprint sensor unit FSU.

The display device may include a first substrate 110 and/or a secondsubstrate 120. For example, a display device may include a display panel100 including the first and second substrates 110 and 120 and displayingan image on one surface (e.g., a front surface) of the second substrate120, a light sensor layer 300 disposed on a rear surface (an oppositesurface to one surface displaying an image) of the display panel 100,and a light guide layer 200 disposed between the display panel 100 andthe light sensor layer 300.

The display panel 100 may include the first substrate 110 and the secondsubstrate 120 on a first surface of the first substrate 110. In anembodiment, the first substrate 110 and the second substrate 120 may beopposed to each other. According to an embodiment, the display panel 100may further include at least one of a polarizing plate 130 and a window140 disposed on the second substrate 120.

According to an embodiment, at least one of the first substrate 110 andthe second substrate 120 may be a glass substrate or a plasticsubstrate. For example, the first substrate 110 and/or the secondsubstrate 120 may be a flexible substrate including at least one ofpolyethersulfone (PES), polyacrylate, polyetherimide (PEI), polyethylenenaphthalate (PEN) polyethylene terephthalate (PET), polyphenylenesulfide (PPS), polyarylate (PAR), polyimide (PI), polycarbonate (PC),cellulose triacetate (TAC), and cellulose acetate propionate (CAP). Inan embodiment, the first substrate 110 and/or the second substrate 120may be a rigid substrate including one of glass and tempered glass.Further, the first substrate 110 and/or the second substrate 120 may bea transparent substrate, that is, a light transmitting substrate.

According to an embodiment, at least one of the first substrate 110 andthe second substrate 120 may include an insulating layer having at leastone inorganic film and/or organic film. For example, the secondsubstrate 120 may be a thin film encapsulation (TFE) layer including atleast one inorganic film and/or organic film.

According to an embodiment, the first substrate 110 may be provided withthe plurality of pixels PXL. For example, the plurality of pixels PXLmay be disposed between the first substrate 110 and the second substrate120. According to an embodiment, each of the pixels PXL may include aplurality of sub-pixels, for example, the first, second and thirdsub-pixels SPX1, SPX2 and SPX3.

Each of the first, second and third sub-pixels SPX1, SPX2 and SPX3 mayinclude a transistor 111 on the first surface of the first substrate 110and the light emitting device 115 electrically connected to thetransistor 111. According to an embodiment, the transistor 111 mayinclude an active layer 1111, a gate electrode 1112, and source anddrain electrodes 1113 and 1114. According to an embodiment, the activelayer 1111 may be disposed on the first substrate 110, and the gateelectrode 1112 may overlap the active layer 1111 with a first insulatinglayer 112 interposed between the layers 1111 and 1112. According to anembodiment, the source and drain electrodes 1113 and 1114 may bedisposed on a second insulating layer 113 located on the gate electrode1112 and connected to the active layer 1111 through a contact holeformed in the first and second insulating layers 112 and 113.

According to an embodiment, a third insulating layer 114 may be disposedon the source and drain electrodes 1113 and 1114, and the light emittingdevice 115 may be disposed on the third insulating layer 114. The lightemitting device 115 may be electrically connected to the transistor 111through a via hole formed in the third insulating layer 114.

The light emitting device 115 may include a first electrode 1151 and asecond electrode 1153 overlapping each other in at least one area and alight emitting layer 1152 interposed between the first and secondelectrodes 1151 and 1153. According to an embodiment, the firstelectrode 1151 and the second electrode 1153 may be an anode electrodeand a cathode electrode, respectively. Depending on a pixel structure,the first electrode 1151 electrically connected to the transistor 111may be a cathode electrode. According to an embodiment, a fourthinsulating layer 116 may be disposed between the light emitting device115 and the second substrate 120.

According to an embodiment, the display panel 100 may include aplurality of light transmitting paths 150 disposed in a periphery of thelight emitting devices 115 included in at least a portion of the pixelsPXL. For example, the display panel 100 may include a plurality of lighttransmitting paths 150 overlapping the pixels PXL and positioned in aspace between the second and third sub-pixels SPX2 and SPX3.

According to an embodiment, the light transmitting paths 150 may bedisposed so as to be deviated from light emitting areas (for example, anarea in which the light emitting layer 1152 is arranged) of the lightemitting devices 115 disposed in a periphery of the light transmittingpaths 150. For example, the light transmitting paths 150 may be disposedat positions where light emitted from the light emitting devices 115 inan oblique direction toward a fingerprint of a user and verticallyreflected from the fingerprint of the user is received. As describedabove, when the fingerprint is sensed by using the light irradiated inan oblique direction on the fingerprint of the user, light and shade ofthe fingerprint may become more distinct, and the fingerprint patternmay be more easily sensed.

According to an embodiment, when the pixels PXL emit light in adirection of the second substrate 120, the light transmitting paths 150may extend in a direction in which at least a portion of light emittedfrom at least one neighboring pixel PXL is reflected. The portion oflight is reflected from a fingerprint/fingertip of a user and istransmitted toward a light receiving device 310. For example, the lighttransmitting paths 150 may extend in a direction perpendicular to theface of the substrate 110 on which the pixels PXL are disposed so as totransmit the reflected light portion in the direction perpendicular tothe face of the substrate 110. According to an embodiment, alongitudinal direction of the light transmitting paths 150 may not beparallel to the face of the substrate 110, and, for example, may beperpendicular to the face of the substrate 110.

According to an embodiment, the light transmitting paths 150 may beformed to selectively transmit only light in a predetermined directionfor the light reflected from the fingerprint/fingertip of the user. Forexample, a vertical hole may be physically drilled into the displaypanel 100, and/or wires or other light shielding elements may notobstruct the light transmitting paths 150.

According to an embodiment, a transparent space in the active area 11may be used as a light transmitting path 150, and the light guide layer210 and a light receiving device 310 may be disposed under the lighttransmitting path 150 so as to overlap the light transmitting path 150.In an embodiment, a light transmitting paths 150 may be/include one ormore portions formed of one or more transparent materials in the firstand second substrates 110 and 120 and a second electrode 1153 of a lightemitting device 115 for transmitting light in a direction intersectingthe display panel 100. In an embodiment, a light transmitting path 150may be/include a hole, opening, or transparent portion formed in thedisplay panel 100 so that light may be transmitted, and the lighttransmitting path 150 may be located in a transparent space betweenlight shielding wires and/or circuit devices provided in the active area11 including the pixels PXL.

According to an embodiment, the light guide layer 200 and the lightsensor layer 300 may be disposed on a rear surface of the display panel100, that is, on the second surface of the first substrate 110. Thelight guide layer 200 and the light sensor layer 300 may include lightguide paths 210 and light receiving devices 310 corresponding to thelight transmitting paths 150 of the display panel 100. For example, thelight guide paths 210 and the light receiving devices 310 may bedisposed under the light transmitting paths 150.

According to an embodiment, when the pixels PXL emit light in adirection of the second substrate 120, the light guide paths 210 mayextend in a direction in which light transmitting through the lighttransmitting paths 150 of the light reflected from thefingerprint/fingertip of the user and incident in the direction of thefirst substrate 110 is transmitted. For example, the light guide paths210 may extend in the same direction as an extension direction of thelight transmitting paths 150, for example, in a direction perpendicularto the display panel 100. In an embodiment, the longitudinal directionof the light guide paths 210 may be perpendicular to the face of thesubstrate 110 on which the pixels PXL are disposed. The light guidepaths 210 may function as a filter for selectively transmitting only aportion of the reflected light corresponding to a predetermineddirection. When the light guide paths 210 are used, the fingerprintsensor unit FSU may be formed without using an additional lens.

According to embodiments, the shape and the size (for example, adiameter, a cross-sectional area and/or a height) of the light guidepaths 210 and the like may be configured and/or optimized. For example,various types of the light guide paths 210 may be formed in the lightguide layer 200 in consideration of various factors such as the amountof received light and resolution required for each fingerprint sensorunit FSU.

According to an embodiment, the light receiving devices 310 may be aphoto-responsive or photo-sensitive device. For example, the lightreceiving devices 310 may be one of a photodiode, a CMOS image sensor,and a CCD camera. The light receiving devices 310 may generate an outputsignal upon/after receiving the light transmitted through the lighttransmitting paths 150 and the light guide paths 210. The output signalsgenerated from the light receiving devices 310 may be input to a drivingcircuit (not shown) and used to generate fingerprint information of auser. In an embodiment, the display device may sense a fingerprintpattern of a finger on the display panel 100 using the output signalsfrom the light receiving devices 310.

According to an embodiment as described above, the fingerprint sensor ofthe display device may sense a fingerprint of a user using the lightemitted from the pixels PXL without requiring an additional lightsource. In an embodiment, by selectively transmitting light using thelight guide paths 210, the fingerprint sensor may not require anadditional lens for forming an image corresponding to the fingerprintpattern. Accordingly, the thickness of the display device may beminimized, and the manufacturing cost of the display device may beminimized.

According to an embodiment, the light sensor layer 300 for sensing thelight reflected from the fingerprint/fingertip of the user and the lightguide layer 200 may be disposed on a rear surface of the display panel100. Accordingly, the light sensor layer 300 may be prevented frominterfering with images viewed by the user; therefore, satisfactoryimage quality of the display device may be attained.

FIG. 14 illustrates an example of a light guide layer shown in FIG. 13.

Referring to FIG. 14, according to an embodiment, the light guide layer200 may be a light shielding layer 201 including a plurality of openingscorresponding to the light guide paths 210. In an embodiment, the lightguide paths 210 may consist of openings or holes formed in the lightshielding layer 201. According to an embodiment, the light shieldinglayer 201 may be a black matrix, and formed of a material having lightshielding property. When the light guide layer 200 is provided by usingthe light shielding layer 201 including the plurality of openings, thefingerprint sensor unit FSU may be embodied without using a separatelens (an additional lens) and decrease in resolution due to diffractionof light may be prevented.

According to an embodiment, FIG. 14 illustrates the light guide paths210 in a cylindrical shape. For example, the shape, size, and/orarrangement structure of the light guide paths 210 may be configuredand/or optimized in embodiments.

FIG. 15 illustrates an example of the light guide layer shown in FIG.13. In FIG. 15, the similar or same elements as those in FIG. 14 aredenoted by the same reference numerals.

Referring to FIG. 15, according to an embodiment, the light guide layer200 may further include a color filter 212 filling the openingsconstituting the light guide paths 210. For example, when the pixels PXLdisposed in the fingerprint sensor area 11 a are driven to emit bluelight and the blue light is used for fingerprint sensing, the colorfilter 212 may be a blue color filter that selectively transmits bluelight. When the predetermined color filter 212 is included in the lightguide paths 210, the light reflected from a finger may be more properlyselected to improve reliability of the fingerprint sensing.

FIG. 16 illustrates an example of the light guide layer shown in FIG.13.

Referring to FIG. 16, according to an embodiment, a light guide layer200′ may include optical fibers (a bundle of optical fibers)constituting light guide paths 210′. In an embodiment, each of the lightguide paths 210′ may be formed of an individual optical fiber includinga core 210 a′ having a relatively high refractive index and a cladding210 b′ surrounding the core 210 a′ and having a lower refractive indexthan the core 210 a′. For example, the light guide layer 200′ may beformed by cutting and disposing a bundle of optical fibers on the rearsurface of the display panel 100 so as to correspond to the lighttransmitting paths 150. According to an embodiment, the light guidepaths 210′ may be embodied as other light guide path using a refractiveindex difference in addition to or instead of the optical fibers.

According to an embodiment, the light guide layer 200′ may furtherinclude a transparent insulating layer 201′ having a refractive indexlower than that of the optical fibers constituting the light guide paths210′ and filling a space between the optical fibers. By using thetransparent insulating layer 201′, the optical fibers may be stablyarranged at positions corresponding to the light-transmitting paths 150and the light-receiving elements 310.

According to an embodiment, the light guide layer 200′ may furtherinclude a color filter (not shown) included in a core 210 a′ of theoptical fibers constituting each light guide path 210′. For example, ablue color filter material may be included in the core 210 a′. The lightreflected from a fingerprint may be more properly selected.

According to an embodiment as described above, the light guide paths210′ may be formed using optical fibers or an optical waveguide with arefractive index difference. Thus, light in a predetermined directiontransmitted through the light transmitting paths 150, for example, lightin a vertical direction, may be selectively incident on the lightreceiving devices 310.

FIG. 17 illustrates a method of fingerprint sensing of a display deviceaccording to an embodiment. In an embodiment, a photodiode is shown asan example of the light receiving device in FIG. 17.

Referring to FIG. 17, when the display device according to an embodimentis driven in the fingerprint sensing mode, at least a portion of thelight emitting devices EL of the pixels included in the fingerprintsensor area 11 a of the display panel 100 may be turned on. At least aportion of the light emitted from turned on light emitting element ELmay be reflected by being hit by a finger of a user. Verticallyreflected light transmitted through the light transmitting paths 150 andthe light guiding path 200 in a corresponding area may be incident on(and received by) the light receiving device 310 (for example, aphotodiode). In an embodiment, only the light reflected from thefingerprint/fingertip (which has ridges and valleys) and transmittedthrough at least one pair of the light transmitting path 150 and thelight guide layer 200 may be selectively incident on the correspondinglight receiving device 310.

The light receiving device 310 supplied with the reflected light maygenerate a corresponding output signal. The output signal of each of thelight receiving devices 310 disposed in the light sensor layer 300 maybe input to a driving circuit (not shown). The driving circuit maygenerate the fingerprint information of a user by collectively using theoutput signals of the light receiving devices 310. For example, ridgesand valleys of the fingerprint/fingertip may be detected by integratingthe output signals from the light receiving devices 310, and the shapeof the fingerprint may be sensed/determined. Thus, the display devicemay provide a fingerprint sensing function.

The light transmitting paths 150 may be arranged so as not to overlapthe light emitting areas of the light emitting devices EL. In anembodiment, the light emitting paths 150 may be disposed at positionswhere light emitted from the light emitting devices EL in an obliquedirection toward the fingerprint/fingertip of the user and verticallyreflected from the fingerprint of the user is received. According to theembodiment, in order to irradiate light on the fingerprint/fingertip ofthe user in an oblique direction, only a portion/subset of the pixelsPXL arranged in the fingerprint sensor area 11 a may be selectivelyturned on, and/or the pixels PXL in the fingerprint sensor area 11 a maybe divided into a plurality of groups and the pixels PXL included inrespective group may be sequentially turned on. When light is irradiatedon the fingerprint/fingertip of the user in an oblique direction, lightand shade of the fingerprint may be more clearly recognized using thecorresponding shade. Thus, the reliability of the fingerprint sensingmay be optimized.

FIG. 18 is a cross-sectional view illustrating a fingerprint sensingarea of a display device according to an embodiment. In FIG. 18, thesimilar or same elements as in FIG. 13 are denoted by the same referencenumerals, and a detailed description thereof will be omitted.

Referring to FIG. 18, the display device according to an embodiment mayfurther include a filter layer 400 disposed between the display panel100 and the light guide layer 200. According to an embodiment, thefilter layer 400 may be a color filter that selectively transmits onlythe light emitted from a portion of the sub-pixels SPX1, SPX2 and SPX3.For example, when sub-pixels that emit blue light, among the sub-pixelsSPX1, SPX2, and SPX3 are turned on for fingerprint sensing during apredetermined fingerprint sensing period, the filter layer 400 may beembodied as a blue color filter that selectively transmits the bluelight. When the filter layer 400 is disposed between the display panel100 and the light guide layer 200, the light reflected from afingerprint and incident on the display panel 100 may be more properlyselected.

FIG. 19 is a cross-sectional view illustrating a fingerprint sensingarea of a display device according to an embodiment. In FIG. 19, thesimilar or same elements as in FIG. 13 are denoted by the same referencenumerals.

Referring to FIG. 19, the display device according to an embodimentfurther includes a touch sensor layer 160 positioned in at least onearea of the active area 11. According to an embodiment, the touch sensorlayer 160 may include at least one touch sensor electrode 162 disposedin a predetermined fingerprint sensor area 11 a in which the fingerprintsensor units FSU are provided of the active area 11. For example, thefingerprint sensor area 11 a may be provided with a plurality of touchsensor electrodes 162 overlapping the pixels PXL and the fingerprintsensor units FSU.

According to an embodiment, the touch sensor layer 160 may be disposedon one surface of the second substrate 120, for example, on an uppersurface of the second substrate. The position of the touch sensor layer160 may be configured and/or optimized according to embodiments. Forexample, the touch sensor layer 160 may be disposed on an inner surface(e.g., a lower surface) and/or an outer surface (e.g., an upper surface)of the second substrate 120 and integrated with the display panel 100.In an embodiment, the touch sensor layer 160 may be separately formedfrom the display panel 100 and attached to at least one surface of thedisplay panel 100. According to an embodiment, the touch sensor layer160 may be a rigid or a flexible touch sensor layer 160 embodied on arigid substrate or a flexible substrate.

According to an embodiment, the touch sensor layer 160 may be utilizedfor fingerprint sensing. For example, whether a finger is touched or notand/or where the finger is touched may be detected in response to thetouch signal from the touch sensor layer 160, and the fingerprintsensing mode may be activated such that a fingerprint sensing period maybe started.

According to an embodiment, an area in which the touch signal isgenerated may be set to the fingerprint sensor area 11 a and the pixelsPXL in the set fingerprint sensor area 11 a may be driven in thefingerprint sensing mode. For example, in a display device in whichfingerprint sensor units FSU are arranged at a predetermined resolutionover the entire active area 11, a predetermined area including an areain which the touch signal is generated may be set to the fingerprintsensor area 11 a in real time.

Further, according to an embodiment, the fingerprint sensor area 11 amay be displayed by concurrently emitting light of a plurality of pixelsPXL arranged in the area in which the touch signal is generated. In thecase of the display device in which only a portion of the active area 11is the fingerprint sensor area 11 a or the touch sensor layer 160 is notprovided, at least a portion of the pixels PXL of the fingerprint sensorarea 11 a may emit light in an initial period of the fingerprint sensingperiod even though the touch signal is not generated. As a result, thefingerprint sensor area 11 a may be displayed, and the user may easilyrecognize the fingerprint sensor area 11 a. According to an embodiment,the light of pixels PXL in a predetermined fingerprint sensor area 11 aor the fingerprint sensor area 11 a detected by the touch sensor layer160 may be emitted to notify the user of the fingerprint sensor area 11a.

Various functions may be provided to the display device using the touchsensor layer 160 for fingerprint sensing.

FIG. 20 is a flowchart illustrating a driving/operating method of adisplay device according to an embodiment. Particularly, FIG. 20 is theflowchart illustrating a driving method of a display device using pixelsas a light source for fingerprint sensing and including a light guidelayer and a light sensor layer arranged on a display panel (for example,on a surface opposite an image-displaying surface of the display panel)in a fingerprint sensing period. In an embodiment, FIG. 21 illustratesan embodiment of a driving method of pixels in a fingerprint sensingarea according to an embodiment. FIG. 21 shows an embodiment of adriving method of pixels in a fingerprint sensor area for a fingerprintsensing period.

Referring to FIG. 20, a method of driving/operating a display device mayinclude step ST10 for activating a fingerprint sensing mode, step ST20for turning on a pixel PXL in the fingerprint sensor area 11 a, stepST30 for receiving light reflected from a fingertip and/or afingerprint, and step ST40 for generating fingerprint information.

According to an embodiment, step ST10 may include activating thefingerprint sensing mode in response to a control signal, such that afingerprint sending period may be started. According to an embodiment,the control signal may be generated according to the decision of a user.In an embodiment, the control signal may be supplied from a system forcontrolling the display device in accordance with contents related toimages to be displayed by the display device.

For example, the user may input a touch signal for activating thefingerprint sensing mode through the touch sensor layer 160 shown inFIG. 19. The control signal for activating the fingerprint sensing modecorresponding to the touch signal by the user may be generated.

According to an embodiment, the area in which the touch is provided maybe set as the fingerprint sensor area 11 a. For example, a predeterminedrange from a point where the touch is provided may be set to thefingerprint sensor area 11 a in real time.

According to an embodiment, the fingerprint sensor area 11 a setaccording to the touch signal may be displayed by simultaneously turningon at least a portion of the pixels PXL in the area in which the touchsignal is generated. Accordingly, the user may easily detect orrecognize the fingerprint sensor area 11 a and touch the correspondingarea for fingerprint sensing.

According to an embodiment, regardless of whether the touch signal isgenerated or not, at the beginning of the fingerprint sensing periodduring which the fingerprint sensing mode is activated, at least aportion of the pixels PXL arranged in the predetermined fingerprintsensor area 11 a may be concurrently turned on, the finger sensor area11 a may be displayed accordingly.

According an embodiment, step ST20 may include turning on at least aportion of the pixels PXL located in the fingerprint sensor area 11 a ata predetermined distance and/or in a predetermined order.

For example, at step ST20, the pixels PXL located in the fingerprintsensor area 11 a, as in the embodiment shown in FIG. 21, may be dividedinto a plurality of groups GR (e.g., 4 groups GR), and the pixels PXLincluded in each group GR may sequentially emit light. Correspondingpixels PXL belong to different groups GR and located at correspondinglocations may emit light simultaneously or may be turned offsimultaneously.

According to an embodiment, at ST20, the fingerprint sensing periodduring which the fingerprint sensing mode is activated may be dividedinto a plurality of sub-periods, only a subset of the pixels PXLarranged at one or more predetermined distances/positions (in each groupGR) may selectively emit light during each sub-period.

According to an embodiment, in terms of driving the pixels PXL in thefingerprint sensing mode, the emission of the pixels PXL may beindividually controlled using a scan signal, a light emitting controlsignal and/or a data signal described with reference to FIGS. 6 and 7.For example, the pixels PXL of the fingerprint sensor area 11 a mayselectively emit light in response to the control signal correspondingto the fingerprint sensing mode. According to an embodiment, the pixelsPXL of the fingerprint sensor area 11 a may be divided into a pluralityof groups GR, and the pixels PXL included in each group GR maysequentially emit light in response to the control signal correspondingto the fingerprint sensing mode.

As in the embodiment shown in FIG. 21, at least a portion/subset of thepixels PXL located in the fingerprint sensor area 11 a may be lit up ata predetermined distance (or location) and/or in a predetermined order,potential crosstalk that may occur between turned on pixels PXL may beminimized or reduced. Thus, the reliability of the fingerprint sensingmay be improved.

According to an embodiment, step ST30 may include receiving the light onthe light sensor layer 300, wherein the light has been reflected fromthe finger and/or the fingerprint of the user and has been transmittedvia the light guide layer 200. For example, at step ST30, lightreflected from a fingerprint may be transmitted through the lighttransmitting paths 150 and the light guide paths 210 of the light guidelayer 200 of the display panel 100 and may be incident on (and receivedby) the light receiving devices 310 of the light sensor layer 300. Thelight receiving devices 310 may generate one or more output signalscorresponding to the received light.

According to an embodiment, step ST40 may include generating fingerprintinformation of the user using the output signals from the lightreceiving devices 310. For example, characteristics of the fingerprintmay be determined by integrating the output signals from the lightreceiving devices 310.

According to an embodiment, step ST40 may include sensing thefingerprint sensor area 11 a, detecting the output signals output fromthe light receiving devices 310 arranged in the fingerprint sensor area11 a, selecting all of the output signals or a subset of the outputsignals, and generating the fingerprint information by synthesizing theselected output signals. According to an embodiment, sensing thefingerprint sensor area 11 a may include sensing or detecting apredetermined fingerprint sensor area 11 a, or setting a new fingerprintsensor area 11 a. For example, a predetermined fingerprint sensor area11 a may be detected using stored area information, or an area in whicha touch signal is generated (e.g., an area within a predetermined rangerelative to a touch) may be set to the fingerprint sensor area 11 a.

According to an embodiment, the generating of the fingerprintinformation may be performed in a fingerprint sensor controller (or afingerprint sensor driver) provided on a driving circuit (not shown) oran integrating controller integrated with a touch sensor controller (or,a touch sensor driver).

According to an embodiment, the sensed fingerprint information may beutilized for various purposes such as identifying a user or registeringa new user. For example, a user may be identified by comparing thefingerprint information of a specific user stored in advance with thefingerprint information sensed through the fingerprint sensor.

According to an embodiment, a display device may include a fingerprintsensor for sensing a fingerprint of a user using light emitted frompixels without using an additional light source. Accordingly, thedisplay device may have a minimized thickness and/or the relatedmanufacturing cost may be minimized.

According to an embodiment, a light sensor layer for sensing lightreflected from a fingerprint of a user may be disposed on a rear surfaceof a display panel. Accordingly, the light sensor layer may notinterfere with images viewed by a user, so that satisfactory imagequality of the display device may be attained.

While embodiments have been described as examples, various modificationsmay be made without departing from the scope defined by the claims.

What is claimed is:
 1. A display device, comprising: a first substrate,which includes light transmitting portions; a plurality of pixelspositioned on the first substrate and including light emitting devices;a light sensor layer overlapping the first substrate and including aplurality of light receiving devices, the light receiving devicesrespectively corresponding to the light transmitting portions andconfigured to output one or more output signals in response to receivedlight; and a light guide layer positioned between the display panel andthe light sensor layer and including a plurality of light guide paths,the light guide paths respectively corresponding to the lighttransmitting portions.
 2. The display device of claim 1, wherein thefirst substrate is positioned between the plurality of pixels and thelight sensor layer.
 3. The display device of claim 1, comprising: asecond substrate, which overlaps the first substrate and includes lighttransmitting parts, wherein the light transmitting parts respectivelycorrespond to the light transmitting portions, and wherein the pixelsare configured to emit light toward the second substrate and arepositioned between the first substrate and the second substrate.
 4. Thedisplay device of claim 1, wherein a longitudinal direction of each ofthe light transmitting portions and a longitudinal direction of each ofthe light guide paths is perpendicular to a face of the first substrateon which the plurality of pixels is arranged.
 5. The display device ofclaim 1, comprising: a plurality of fingerprint sensor units including afirst fingerprint sensor unit, the first fingerprint sensor unitincluding a first light transmitting portion among the lighttransmitting portions, a first light receiving device among the lightreceiving devices, and a first light guide path among the light guidepaths, wherein the first light transmitting portion, the first lightreceiving device, and the first light guide path correspond to oneanother.
 6. The display device of claim 5, wherein the pixels include afirst pixel, wherein the first pixel comprises two subpixels immediatelyneighboring each other, wherein a geometric axis of the first lightguide path coincides with a boundary between the two subpixels.
 7. Thedisplay device of claim 5, wherein, in a predetermined portion of thedisplay device, a total quantity of the fingerprint sensors is equal toa total quantity of the pixels or is equal to a fraction of the totalquantity of the pixels.
 8. The display device of claim 5, wherein thefirst fingerprint sensor unit overlaps at least one of the pixels. 9.The display device of claim 5, wherein the pixels include a first pixel,wherein the first pixel comprises two subpixels immediately neighboringeach other, wherein the first light receiving device is positioned at aboundary between the two subpixels.
 10. The display device of claim 1,wherein the light guide paths include a first light guide path, whereinthe pixels include a first pixel, wherein the first pixel comprises afirst subpixel and a second subpixel immediately neighboring each other,wherein the first light guide path is positioned between a lightemitting device of the first subpixel and a transistor of the secondsubpixel.
 11. The display device of claim 10, wherein the first lightguide path is positioned between a first electrode of the light emittingdevice of the first pixel and an active layer of the transistor of thesecond pixel.
 12. The display device of claim 1, wherein the light guidepaths are openings, through holes, or transparent portions of the lightguide layer, and wherein the light guide layer includes light shieldingportions positioned between the light guide paths.
 13. The displaydevice of claim 1, wherein the light guide paths include color filters,and wherein the light guide layer further includes light shieldingportions positioned between the color filers.
 14. The display device ofclaim 1, wherein the light guide paths include optical fibers.
 15. Thedisplay device of claim 14, wherein the light guide layer furtherincludes transparent insulating portions positioned between the opticalfibers, and wherein a refractive index of each of the transparentinsulating portions is less than a refractive index of each of theoptical fibers.
 16. The display device of claim 14, wherein a core ofeach of the optical fibers includes a color filter material.
 17. Thedisplay device of claim 1, further comprising: a color filter layerpositioned between the first substrate and the light guide layer. 18.The display device of claim 17, wherein each of the pixels includes aplurality of sub-pixels emitting light in different colors, wherein thedifferent colors include a first color, and wherein the color filterlayer has the first color.
 19. The display device of claim 1, whereinthe light guide paths include a first light guide path, which comprisesa first cladding and a first core surrounded by the first cladding,wherein the light guide layer comprises an insulating portionsurrounding the first cladding, wherein a refractive index of the firstcore is greater than a refractive index of the first cladding, andwherein the refractive index of the first cladding is greater than arefractive index of the insulating portion.
 20. The display device ofclaim 1, wherein the light guide paths include a first light guide path,wherein the pixels include a first pixel, wherein the first pixelcomprises a first subpixel and a second subpixel immediately neighboringeach other, wherein the first light guide path is positioned between alight emitting device of the first subpixel and a light emitting deviceof the second subpixel.
 21. The display device of claim 1, furthercomprising: a touch sensor layer, which comprises touch sensorelectrodes, the touch sensor electrodes respectively overlapping thepixels and respectively overlapping the light guide paths.
 22. Thedisplay device of claim 21, wherein the touch sensor electrodes includea first touch sensor electrode, wherein the light guide paths include afirst light guide path overlapping the first touch sensor electrode andpositioned between a first edge of the first touch sensor electrode anda second edge of the first touch sensor electrode, and wherein a minimumdistance between the first edge of the first touch sensor electrode andthe first light guide path is greater than a minimum distance betweenthe second edge of the first touch electrode and the first light guidepath.
 23. The display device of claim 1, wherein a first subset of thepixels is configured to emit light in response to a control signal toindicate a fingerprint sensing area when a second subset of the pixelsemits no light.
 24. The display device of claim 1, wherein the pixelsform a plurality of pixel groups, and wherein pixels included in one ofthe pixel groups are configured to sequentially emit light in responseto a control signal.
 25. A method of operating a display device, thedisplay device comprising a first substrate, a plurality of pixelspositioned on the first substrate and having light emitting devices, alight sensor layer overlapping the first substrate, and a light guidelayer positioned between the first substrate and the light sensor layer,the method comprising: starting a fingerprint sensing period in responseto a control signal; turning on a first subset of the pixels during thefingerprint sensing period to emit first light toward at least one of afinger and a fingerprint; receiving second light using the light sensorlayer, wherein the second light is a portion of the first light that isreflected from the at least one of the finger and the fingerprint and istransmitted via the light guide layer; generating an output signalcorresponding to the second light; and generating fingerprintinformation using the output signal.
 26. The method of claim 25,comprising: turning off or keeping off a second subset of the pixelswhen the first subset of the pixels is on, wherein pixels of the secondsubset are positioned between pixels of the first subset and separatethe pixels of the first subset from one another.
 27. The method of claim25, wherein the fingerprint sensing period includes a first sub-periodand a second sub-period immediately following the first sub-period,wherein the first subset of the pixels emits the first light in thefirst sub-period, wherein a second subset of the pixels emits no lightin the first sub-period, wherein the first subset of the pixels emits nolight in the second sub-period, and wherein the second subset of thepixels emits third light in the second sub-period.
 28. The method ofclaim 25, comprising: generating the control signal in response to atouch provided by the finger on the display device.
 29. The method ofclaim 28, comprising: setting a fingerprint sensing area based on alocation of the touch; and selecting the first subset of the pixelsbased on the fingerprint sensing area.
 30. The method of claim 29,comprising: indicating, in response to the touch, the fingerprintsensing area by concurrently turning on at least pixels that are locatedin an area of the display device corresponding to the touch.
 31. Themethod of claim 25, comprising: indicating a fingerprint sensing area byconcurrently turning on the first subset of the pixels for apredetermined initial period of the fingerprint sensing period, whereinthe first subset of the pixels is located in the fingerprint sensingarea.